An additional horror of this disease is that it's a dominant gene - you have a 50-50 chance of inheriting it from a parent with Huntington's. By the time it was diagnosed, the victim had almost always already married and had kids, passing it on to another generation.
It looks like Arlo Guthrie (of "Alice's Restaurant" fame) has dodged the bullet, I don't think he or any of his surviving siblings ever got tested, but he's well beyond the age when the first symptoms develop.
In the majority of cases, that's true. I personally know someone who had no symptoms until age 58. I hope Arlo will continue to 'dodge the bullet' ... it's a disease I certainly wouldn't wish on him, or on anyone else.